Soil moisture−atmosphere feedbacks have triggered the shifts from drought to pluvial conditions since 1980

Abstract

Drought and pluvial transitions have attracted widespread attention. However, the dynamic evolution and underlying mechanisms of drought and pluvial transitions remain poorly understood. Here, we demonstrate that there is a significant increase in the occurrence of drought and pluvial transitions (0.24−1.03% per year) globally during 1980−2020. We use convergent cross mapping to detect causal relationships between time series variables in the climate system and find that drought and pluvial transitions can be explained by an indirect transitive causal chain. Specifically, the soil moisture−latent heat flux−precipitation causal chain is likely to trigger the rainfall following the dryness in humid regions where enhanced evaporation increases the actual atmospheric moisture favoring the pluvial occurrence. By contrast, the soil moisture−moisture convergence−precipitation causal chain enhances the post-drought rainfall in arid regions due to atmospheric circulation dynamics. Our results indicate that land−atmosphere feedbacks play an important role in triggering the drought-pluvial shift in a changing climate.